The class is a simple java class which acts like a scheduler and which should start with server start-up and it depends on few other class files. All of these class files are packaged in a jar file. Is there a way I can tell Weblogic to read that jar and call my class (it has a main method) at startup..??

WebLogic Server console has a place where you can enter the fully qualified Java class name. This class gets called at the time of server startup. All you have to ensure is that the class file or the jar (which contains the class) is present in the classpath.

Both Startup and Shutdown Classes are provided for doing life cycle maintenance activities.